Twenty-nine minutes after buying ammunition for a .38-caliber revolver at a Walmart, three men in a white sport utility vehicle opened fire early Sunday in Easton's West Ward, the start of a bloody rampage that left three dead, authorities said Tuesday in announcing arrests.

That couple was spared when the shooter missed his mark, but authorities said the spree of indiscriminate shooting was not over.

The men in the SUV made their way to Allentown, where they opened fire on Francine E. Ramos, 32, and Trevor D. Gray, 21, two Allentown residents riding in a car near Sixth and Greenleaf streets, authorities said.

Ramos crashed into the SUV in an attempt to get away, authorities said, but she was found dead in her car at 3:59 a.m. Gray died a short time later.

At separate news conferences detailing the violent crime spree, authorities in Lehigh and Northampton counties said they did not know why the three men arrested — one from Easton and two from New Jersey —fired at people randomly early Sunday morning.

"Based on the evidence, all of these acts, all of them, appear to be completely random," Lehigh County District Attorney Jim Martin said Tuesday afternoon.

Robert A. Jourdain, 20, of Easton; Todd West, 22, of Elizabeth, N.J.; and Kareem Mitchell, 23, of Newark, N.J., were arrested Monday and face three counts of homicide in the killings, and two counts of attempted homicide in the downtown Easton shooting.

Jourdain and West also were charged in three Allentown knifepoint muggings that happened the day after the killings, police said. They were arrested when Allentown patrolmen chased them down minutes after the third Monday morning mugging. Mitchell turned himself in later that day.

Martin wouldn't say if the three men had any known gang connections. West was being held on fugitive charges related to a homicide in Union County, N.J., but Martin wouldn't comment on that case.

West is wanted in New Jersey by detectives investigating the deaths of three men gunned down in Elizabeth, N.J., and neighboring Linden, N.J., over a 90-minute period June 25, according to Union County Crime Stoppers.

The Union County prosecutor's office confirmed Tuesday it had charged West with murder in one of the June 25 deaths, according to nj.com.

West admitted firing the gun in the three killings and two attempted homicides in the Lehigh Valley, according to court records.

Martin and Northampton County District Attorney John Morganelli praised the work of investigators in both counties.

"This was a complex case that was resolved in less than 48 hours after a man and woman were found shot to death in Allentown," Martin said. "This case is an excellent example of law enforcement authorities working together to apprehend these three men.

"The quick developments in the case were the result of their efforts at collecting evidence, interviewing witnesses and making connections that linked the incidents in Northampton and Lehigh counties," he said.

Martin said the cellphones of the three arrested men are being analyzed. He said Kurt J. Tempinski, a Lehigh County detective and ballistics expert, analyzed the recovered casings and bullet fragments recovered from the victims and the crime scenes, which helped link the shootings.

"Without that lab and Detective Tempinski, we may have been waiting for days or weeks to get results, but they were obtained in hours," Martin said. "That was crucial to the investigation."

The violence began after Jourdain, of the first block of North Fourth Street in Easton, bought ammunition for a .38-caliber gun at the Walmart in Lower Nazareth Township, authorities said.

According to court records:

Mitchell drove Jourdain and West to the Walmart at 3722 Easton-Nazareth Highway. There, surveillance footage captured Jourdain buying the ammunition at 2:45 a.m. Sunday. After Jourdain bought it, West drove them "away from Walmart with the gun and newly purchased ammunition."

The shootings began less than 30 minutes later when Ketrow was shot once in the chest and once in the back along Lehigh Street, just a few doors from his home, Morganelli said at a Tuesday morning news conference. Ketrow was rushed to Easton Hospital, where he died within an hour.

While Easton police were picking up evidence at the Lehigh Street shooting — and Ketrow was still alive — detectives received a call from Palmer Township police, Morganelli said.

A 46-year-old woman and 45-year-old man had rushed to the Palmer police station to report they'd been shot at about 3:20 a.m. The couple said they were driving near Third and Spring Garden streets in Easton when a vehicle pulled up behind them, a man stepped out and fired a gun at them.

Detectives said they later recovered a bullet from the tire of the couple's SUV.

"[The shootings] appear to be random acts," Easton police Lt. Matthew Gerould said. "There was no connection between our victims and the suspects."

While Easton detectives were investigating the two shootings, Allentown police were dispatched at 3:59 a.m. to a reported shooting and crash at Sixth and Greenleaf streets.

Police found Ramos' burgundy sedan had crashed into a parked car in the northwest corner of the intersection. Ramos was found behind the wheel of her car, dead from several bullet wounds. Gray was slumped over the parked car and died as paramedics tried to help him, according to court records.

At the time, Allentown police knew only that the vehicle possibly involved in the shooting and crash was white or light-colored, Martin said. Vehicle parts were found at the scene, he said.

Allentown investigators learned of the shootings in Easton and the two departments compared notes. A witness to the attempted homicide in Easton told police that the shooters fled in a white Mercedes SUV, Martin said, describing that information as a big break in the case.

An Allentown police officer Sunday morning spotted a damaged white Mercedes SUV in a parking lot in the 400 block of Hamilton Street, a half-block from police headquarters.

After obtaining a search warrant, police searched the vehicle and found a .38-caliber Smith & Wesson revolver in a Walmart bag, along with 18 discharged .38-caliber casings, court records show.

Police learned that the SUV was owned by Mitchell's mother and they were able to talk to Mitchell by phone late Sunday, Martin said. Mitchell agreed to speak with police in person Monday afternoon, Martin said.

Martin said the three men intended to come back for the damaged SUV, but police got to it before they could.

As police investigated the killings, they say, Jourdain and West committed three robberies using a knife Monday morning.

According to court records:

At 6:27 a.m., Jourdain and West roughed up a man and stole his cellphone and $20 in the 400 block of Whitehall Street.

At 8:57 a.m., the two forced another man to the ground at knifepoint and stole a green lighter and $9 in the 500 block of North Morris Street.

And at 9:09 a.m., Jourdain and West pressed a knife to a man's neck in the 600 block of North Mohr Street.

Martin said one of the victims suffered a cut to the hand and another passed out, both requiring treatment at the hospital.

About 20 minutes after the third robbery, Allentown police officer James Nuskey noticed two men near Morris and Washington streets whose clothing fit descriptions provided by the robbery victims, police said.

Nuskey approached the two men, who ran but were captured after a foot chase, police said. They were later identified as Jourdain and West, police said.

That afternoon, detectives interviewed all three men, with each admitting their role in the crimes, according to court records. Mitchell admitted driving Jourdain and West to the Walmart where Jourdain bought ammunition, records show.

West admitted shooting Ketrow, Ramos and Gray and firing at the Easton couple, records show. He didn't say why.

All three men were arraigned by District Judge Patricia Engler and are being held in Lehigh County Jail without bail.

In keeping with their usual policy, prison officials in Northampton County and New Jersey provided mug shots of Jourdain and West. Lehigh County officials do not typically provide mug shots, and didn't provide one of Mitchell.